This K23 Mentored Patient-Oriented Research Career Development Award describes training in methods to study developing social brain function in infants at-risk for autism spectrum disorder (ASD). The applicant is a child clinical psychologist with clinical expertise in ASD and previous experience studying the neural correlates of face perception in children with ASD. Through formal training and a related research project, this application will provide additional research experience necessary for successful independent investigation in the field of patient-oriented research. The training goals of the project entail: (1) expanding knowledge of the electroencephalogram (EEG) as an investigative tool by training in neurophysics and advanced data processing and analysis; (2) learning to apply EEG methodology to investigate (a) a new population, infants, and (b) a new sensory modality, auditory perception; (3) co-registering measures of visual attention (eye- tracking) and brain response (EEG); and (4) obtaining additional training in developmental theory, especially regarding developmental social neuroscience. Integrated with each of these goals is (5) an overarching emphasis on training in the responsible conduct of research. Didactic and practical training will be overseen by experts in infant visual and auditory EEG, infant neurology and epilepsy, infant visual perception, and developmental neuroscience and will take place at the Yale Child Study Center and mentors' facilities at Harvard University and the University of Louisville. The research project applies this training to a longitudinal study of 60 infants at-risk for ASD and 40 low-risk infants. Three experiments will be administered at 4 time points (6, 12, 18, and 24 months) to contrast social and non-social perception using static visual stimuli (mother/stranger face versus familiar/unfamiliar object), auditory stimuli (mother/stranger voice versus non- speech analogs), and dynamic audio-visual stimuli (naturalistic video clips of mother/stranger speaking versus non-biological motion and sounds). These experimental probes will map behavioral and brain specialization for social information in infancy in typical and atypical development. This career development plan expands the applicant's program of research to advance a long-term goal of independent investigation of developing social brain circuitry across the lifespan. The proposed research and the broader career objectives will elucidate early brain dysfunction in ASD for earlier detection and more effective intervention.